In typical bridges, girders extend between piers to support a bridge deck. Shear connectors secure the bridge deck to the girders and prevent the bridge deck from sliding during normal loading. Optimal bridge span design typically requires composite cooperation between the bridge decks and girders to maximize the load bearing capacity of the span. With composite design, structural integrity is enhanced, safety is increased, material requirements and cost are reduced. When the earth supporting the bridge moves however, such as during an earthquake, the shear connectors fail. Accordingly, the shear connectors may to permit movement of the bridge deck. This bridge deck movement reduces stress on supporting piers to prevent damage to the supporting piers and possible collapse.
Two types of shear connectors include pin-type shear connectors as shown in FIG. 4 and channel-type shear connectors as shown in FIG. 5. Pin-type shear connectors are vertically aligned metal studs which have a first end welded to the top flange of a girder and a second end which extends upward for attachment with a bridge deck. The channel-type shear connectors are horizontally aligned metal rods having a "C" shaped profile. The bottom surface of each connectors is welded horizontally across the top flange of a girder and the top of the shear connector extends upwardly from the top flange to attach with a bridge deck.
Two major problems are associated with the welded attachment of above described shear connectors. Firstly, each weld made on a steel girder, reduces girder strength in the area of the weld. Girder strength is crucial where the girder experiences a negative bending moment and the top flange of the girder is in tension. Accordingly girder size and strength design must be adapted to compensate for weakness due to the weld, or the weld could cause failure of the girder. In view of these problems, the use of welded shear connectors is generally avoided in the regions of the girder experiencing tension and negative bending moments. Because the use of shear connectors is limited, ideal composite cooperation is not achieved and overall bridge safety and load bearing capacity may be compromised.
A second problem is that the above described shear connecters have a tendency to fail due to fatigue stress. Fatigue stress considerations require closer spacing and a greater number of shear connectors than would otherwise be required. Bridge construction costs are increased.
In view of the above limitations, the present inventive concept was developed and provides an improved shear connector. The improved shear connector firmly connects a bridge deck to a girder to achieve a composite structure. Welds which reduce girder strength are not required. Fatigue stresses are reduced.